1. Field of the Invention:
This invention relates to an improved cutting assembly in the form of a torary head for a rotary lawn mower, edger, trimmer or the like. The preferred embodiments are in the form of portable hand-held type lawn mowing and edging tools wherein the cutting element is safe in most uses and avoids the hazardous conditions created by prior art devices. More particularly, this invention embodies an improvement over the type of assembly generally depicted in U.S. Pat. No. 3,826,068.
2. Description of the Prior Art:
The prior art is prolix with attempts at solutions to provide a safe, efficient, and simply constructed rotary head for rotary lawn mowers, edgers, trimmer and the like. Heretofore, the rotary head, or cutting blade, of rotary lawn mowers, edgers, and the like, have comprised a rotating metal bar or the like which is rotated at sufficient speeds to effect cutting of grass, weeds, or the like. However, such bars create hazardous conditions in that when they strike certain objects they act upon those objects in a fashion to create and project dangerous missiles which may strike the operator or individuals in the area of work.
Various attempts have been made to overcome the aforesaid hazardous conditions created with rigid-type metal cutting blades of the prior art. Most of these attempts to overcome the problem involve the utilization of some type of flexible flail which will have sufficient resiliency so as not to propel objects which are struck at high velocities. Most of these resilient-type cutting elements of the prior art suffer a disadvantage in that they are not safe and mere resiliency is not sufficient to insure that the dangerous conditions will not be created when rotation is effected at desired cutting speeds. Further, the prior art cutting elements are generally not provided with means for easy replaceability in the event of wearing out and are usually expensive to replace.
The result has been that most of the prior lawn edging apparatus have been unsatisfactory because of the dangerous conditions created by the rotating head. As a consequence, most lawn edging and trimming around trees and the like, which would otherwise be damaged by the metal blades, must be done manually, which is both laborious and time consuming.
There is depicted and described in U.S. Pat. No. 3,826,068, an embodiment of a rotary lawn mower, edger, trimmer or the like, having a disc-like head member arranged to be rotated by a motor, and containing four spools housed therein in diametrically opposed relationship to the shaft of the motor. A length of flexible non-metallic line is coiled about each of the four spools, whereby the free travelling end of each of the four lines extends generally peripherally from its respective spool and the head and whereby the free travelling ends of the four lines will be swung arcuately about upon actuation of the motor to cut vegetation and the like and with the four lines each acting in the fashion of flails.
Use of the device of U.S. Pat. No. 3,826,068, has revealed that, under ideal operating conditions, it will mow, cut, edge, and trim grass and other vegetation effectively. Furthermore, it possesses the significant advantage that it is much safer to use then the more conventional cutters, in that it does not cause stones or other solid objects to be discharged in a dangerous manner, and it is almost completely incapable of causing any significant injury to persons or pets struck by any one or more of the flail line members. In fact, it is a reasonable statement that the device of U.S. Pat. No. 3,826,068, will actually cut substantially only the vegetation to which it is directed.
On the other hand, however, the device of U.S. Pat. No. 3,826,068, is also subject to certain disadvantages such as to limit its practical value to some degree. In the first place, it is of complex construction and is difficult to manufacture by virtue of its four spool arrangement. This multi-spool arrangement results in a device possessing a very complex internal construction. In the second place, the four spool construction of the device renders the device cumbersome to use and cumbersome to repair. The cumbersome construction of four spools also results in unnecessary tangling of the four flail line members. Another disadvantage of the device of U.S. Pat. No. 3,826,068, is that by virtue of its possessing four flail line members, breakage of any one of the lines during use of the device results in unbalancing of the head during rotation. Thus, the fact that the device possesses four flail lines results in more opportunity for line breakage with the result that there is more chance for head unbalance.
These disadvantages of the prior art, and especially the aforementioned U.S. Pat. No. 3,826,068, are overcome with the present invention, and a commercially acceptable vegetation cutter and the like are provided which is not only fully capable of cutting vegetation under most operating conditions, but which is also fully capable of other tasks beyond the capabilities of the device of U.S. Pat. No. 3,826,068. More particularly, however, the embodiment of the present invention is simpler and easier to construct, possesses a less complex internal construction, and eliminates the cumbersome multi-spool arrangement, without sacrifice of the safety features and advantages accorded to the device of U.S. Pat. No. 3,826,068, and provides a more balanced head in the event of line breakage during operation. Thus, the present invention includes a single spool of compound construction versus the multi-spools of the device of the aforesaid U.S. patent.
It is therefore a feature of this invention to provide an improved cutting head or assembly for rotary lawn mowers, edgers, trimmers or the like, which will provide a solution to the aforesaid problems and provide a rotating cutting assembly which is safe for use, which eliminates the aforesaid manual labor, and which can be operated with a minimum of skill.